1. Field of the Invention
The present invention relates to a transistor control device in use for a power transistor chopper, and more particularly to a control device for controlling a transistor base current in the ON-OFF control of a chopper transistor.
2. Description of the Prior Art
In the power transistor chopper for controlling a DC motor for driving a battery car, a speed of a DC motor is controlled by controlling the ON-duty in the ON-OFF control of a transistor connected between a DC power source and the DC motor. The transistor used in such power chopper requires a relatively large base current. In order to feed a base current to the transistor, hitherto, it has been arranged to feed the base current from a power source through a resistor. This arrangement, however, has a problem in that the electrical power loss is large due to the resistor. To solve this problem, it has been also proposed to use a switching regulator. This approach has also a disadvantage that expensive circuit components must be used.